With many of Earth's metals and minerals facing a supply crunch in the decades ahead, deep ocean mining could provide a way of unlocking major new resources. Amid growing commercial interest, the UN's International Seabed Authority has just issued seven exploration licences.

Credit: Nautilus Minerals Inc.

To build a fantastic utopian future of gleaming eco-cities, flying cars, robots and spaceships, we're going to need metal. A huge amount of it. Unfortunately, our planet is being mined at such a rapid pace that some of the most important elements face critical shortages in the coming decades. These include antimony (2022), silver (2029), lead (2031) and many others. To put the impact of our mining and other activities in perspective: on land, humans are now responsible for moving about ten times as much rock and earth as natural phenomena such as earthquakes, volcanoes and landslides. The UN predicts that on current trends, humanity's annual resource consumption will triple by 2050.

While substitution in the form of alternative metals could help, a longer term answer is needed. Asteroid mining could eventually provide an abundance from space – but a more immediate, technically viable and commercially attractive solution is likely to arise here on Earth. That's where deep sea mining comes in. Just as offshore oil and gas drilling was developed in response to fossil fuel scarcity on land, the same principle could be applied to unlock massive new metal reserves from the seabed. Oceans cover 72% of the Earth's surface, with vast unexplored areas that may hold a treasure trove of rare and precious ores. Further benefits would include:

• Curbing of China's monopoly on the industry. As of 2014, the country is sitting on nearly half the world's known reserves of rare earth metals and produces over 90% of the world's supply.

• Limited social disturbance. Seafloor production will not require the social dislocation and resulting impact on culture or disturbance of traditional lands common to many land-based operations.

• Little production infrastructure. As the deposits are located on the seafloor, production will be limited to a floating ship with little need for additional land-based infrastructure. The concentration of minerals is an order of magnitude higher than typical land-based deposits with a corresponding smaller footprint on the Earth's surface.

• Minimal overburden or stripping. The ore generally occurs directly on the seafloor and will not require large pre-strips or overburden removal.

• Improved worker safety. Operations will be mostly robotic and won't require human exposure to typically dangerous mining or "cutting face" activities. Only a hundred or so people will be employed on the production vessel, with a handful more included in the support logistics.

Credit: Nautilus Minerals Inc.

Interest in deep sea mining first emerged in the 1960s – but consistently low prices of mineral resources at the time halted any serious implementation. By the 2000s, the only resource being mined in bulk was diamonds, and even then, just a few hundred metres below the surface. In recent years, however, there has been renewed interest, due to a combination of rising demand and improvements in exploration technology.

The UN's International Seabed Authority (ISA) was set up to manage these operations and prevent them from descending into a free-for-all. Until 2011, only a handful of exploration permits had been issued – but since then, demand has surged. This week, seven new licences were issued to companies based in Brazil, Germany, India, Russia, Singapore and the UK. The number is expected to reach 26 by the end of 2014, covering a total area of seabed greater than 1.2 million sq km (463,000 sq mi).

Michael Lodge of the ISA told the BBC: "There's definitely growing interest. Most of the latest group are commercial companies so they're looking forward to exploitation in a reasonably short time – this move brings that closer."

So far, only licences for exploration have been issued, but full mining rights are likely to be granted over the next few years. The first commercial activity will take place off the coast of Papua New Guinea, where a Canadian company – Nautilus Minerals – plans to extract copper, gold and silver from hydrothermal vents. After 18 months of delays, this was approved outside the ISA system and is expected to commence in 2016. Nautilus has been developing Seafloor Production Tools (SPTs), the first of which was completed in April. This huge robotic machine is known as the Bulk Cutter and weighs 310 tonnes when fully assembled. The SPTs have been designed to work at depths of 1 mile (1.6 km), but operations as far down as 2.5 miles (4 km) should be possible eventually.

As with any mining activity, concerns have been raised from scientists and conservationists regarding the environmental impact of these plans, but the ISA says it will continue to demand high levels of environmental assessment from its applicants. Looking ahead, analysts believe that deep sea mining could be widespread in many parts of the world by 2040.